This is AWESOME:
Digital Urban posted that video just the other day, and as they say, the potential is fantastic. More from them:
All you need to make ARplug-in [for sketchup] work is a personal computer, a webcam and a printed code attached to the software.
For optimal functionality, a Dual-core PC with a standard graphic card for 3D videogames are recommended, see AR-media for full details and download.
A free demo version is available with the full version coming in at 99 euros.